Russian scientists have said they may have identified the missing remains of two of Tsar Nicholas II's children, who were executed after the revolution.

Experts said it was "highly probable" the remains found near Yekaterinburg in July were Alexei, the heir to the throne, and Maria, his elder sister.

They were missing when most of the family's remains were found in 1991.

The tsar, his wife and five children were shot dead by a Bolshevik firing squad in Yekaterinburg on 17 July 1918.

In 2000, the Russian Orthodox Church canonised the royal family, saying they had undergone suffering with gentleness, patience and humility.

Forensic tests

Citing preliminary forensic and DNA tests, the deputy forensic chief scientist in the Sverdlovsk region said the appearance, age and sex of the remains they found mean it was "highly probable" they belonged to Alexei and Maria.

"On the basis of the expert analysis, it is possible to conclude with a large degree of certainty that parts of the skeleton... belong to Tsarevich Alexei and his sister, Grand Duchess Maria Nikolayevna Romanova", Vladimir Gromov told Russian media.

The BBC's James Rodgers in Moscow says the whereabouts of the missing Romanov children has been one of the great unsolved mysteries of Russia's blood-soaked revolution.

After they were shot, the bodies of the tsar and the remainder of his family were burned, doused with acid and thrown into a pit.

They were exhumed in 1991, after the collapse of the Soviet Union.

Final identification of the rest of their family took years, and they were ceremonially buried at the St Peter and Paul Cathedral in St Petersburg in 1998.

Even since then, some members of the Russian Orthodox Church have continued to question the scientists' conclusions, our correspondent says.